Refrigeration apparatus



July 13, 1943 G. s. M cLoY REFRIGERATION APPARATUS Filed Aug. 6, 1942INVENTOR GRRHRM 5. MCCLQY.

Fla. 1.

WITNESSES:

BY E g ATTORN Y Patented July 13, 1943 REFRIGERATION APPARATUS Graham S.McCloy, Springfield, Mass, assignor to Westinghouse Electric &Manufacturing Company, East Pittsburgh, Pa., a corporation ofPennsylvania Application August 6, 1942, Serial No. 453,763

5 Claims.

My invention relates to refrigeration apparatus and particularly toautomatic defrosting of the cooling element of such apparatus.

It is desirable to defrost the cooling element of a refrigerator veryfrequently, for example every day, to obtain maximum heat transferbetween the cooling element and the media to be refrigerated. It has,therefore, been the practice in some cases to provide a defrosting clockwhich renders the refrigerating system inactive every twenty-four hoursfor a suflicient time to effect defrosting.

However, the major portion of the moisture which is condensed and formsfrost on the cooling element is obtained from the air in therefrigerator. Each time the refrigerator door is opened, a charge ofmoisture laden air enters the refrigerator, it being obvious, therefore,that the amount of frost on the cooling element is in nearly directratio for given average cooling element temperatures to the number ofdoor openings. A clock defrosting device has no relation to the amountof frost on the cooling element, with the result that if therefrigerator door is not opened for twenty-four hours, the refrigeratorcooling element is defrosted when it is unnecessary, thereby raisingthe'temperature of the refrigerator and its contents and requiringadditional unnecessary power consumption after defrosting to reduce thetemperatures to normal. On the other hand, if the refrigerator is beingused constantly and the door is being opened many times in a day,defrosting may be necessary in less than twenty-four hours. Defrostingdevices directly responsive to the thickness of frost on the coolingelement are either quite complicated or lack dependability.

It is, therefore, an object of my invention to provide intermittentdefrosting of the cooling element of a refrigerator in response to anoperation or use of the refrigerator which has substantially a directrelationship with the quantity It is a further object of my invention topro-1 vide a defrosting device responsive to refrigerator door openingsfor initiating a defrosting period and responsive to the cooling elementtemperature for ending a defrosting period and restoring normaloperation of the refrigerating system.

,These and other objects are effected by my invention as will beapparent from the following description and claims taken in connectionwith the accompanying drawing, forming a part of this application, inwhich:

Fig. l is a sectional view of a refrigerator cabinet and mechanismembodying my invention; and,

Fig. 2 is a schematic view of a mechanism to initiate and terminate adefrosting period in ,accordance with my invention.

Referring specifically to the drawing for a detailed description of myinvention, numeral H designates generally a refrigerator cabinet havinga food-storage compartment 12 and a machinery compartment l3. Thefood-storage compartment is provided with an access opening 84 closed bya hinged door l5. An evaporator or cooling element 16 refrigerates theair in the food-storage compartment [2 to preserve food stored therein.

A hermetically sealed motor compressor unit H, a condenser l8 and amotor driven fan IQ for cooling the condenser are disposed in themachinery compartment I3. The refrigerating system is of the compressiontype having a motor 2| driving a compressor 22. Compressed refrigerantvapor is delivered to the condenser l8 wherein it is condensed by thecool air from the fan l9. Condensed refrigerant is delivered through acapillary tube flow restricting device 23 to the evaporator l6 whereinthe condensed refrigerant vaporize s and absorbs heat. Refrigerant vaporis withdrawn from the evaporator l6 through a conduit 24 by thecompressor 22, whereupon the refrigeration cycle is repeated.

A standard adjustable temperature control, shown diagrammatically at 25,is provided for normally controlling cyclic operation of the motor 2|and compressor 22 to maintain an average evaporator temperature belowthe freezing point of water, at which temperature moisture is condensedfrom the air in the food-storage compartment l2 and is deposited on theevaporator [6 in the form of frost.

As stated hereinbefore, intermittent automatic defrosting of theevaporator 16 is effected in response to the number of times the door I5is opened. A mechanism for initiating a defrosting period in response todoor openings and terminating said defrosting period in response to ingmoved from one tooth to another.

evaporator temperature is indicated generally at 33. The mechanism 28comprises an operating plunger 21 which is forced inwardly each time thedoor I is closed. A tension spring 23 is attached to the plunger 21 andto a portion 33 of the refrigerator cabinet Ii to pull the plunger 21outwardly when the door I3 is opened. The plunger 21 is attached to afreely rocking lever 3| having a pawl 32 attached thereto. A ratchetwheel 33 having teeth 34 is rotated by movement of the plunger 21, lever3i and pawl 33, the pawl 33 engaging the teeth 34 of the ratchet wheel33. A retaining pawl 35 also engages the teeth 34 and allows rotation ofthe ratchet wheel 33 in a clockwise directbn, but prevents it in acounter-clockwise direction while the pawl 32 is be- The ratchet wheel33 is provided with a fixed arm 33 which engages a snap-acting device 31to open a set of contacts 33. A stop 39 limits the movement of thesnap-acting device 31. The contacts 38, when closed, establish a flow ofcurrent to the temperature control devic 25 and motor 2| through asource of power L1, L2 and when open, interrupt said flow of current.After the arm 36 has operated the snap-acting device 31 to open thecontacts 38, the evaporator l6 rises in temperature due to heat leakageinto the refrigerator cabinet I l, and the evaporator is defrosted aftera short period of time.

When the evaporator temperature reaches a predetermined temperatureabove the freezing point of water to insure that all the frost hasmelted oif, expansible fluid contained in a bulb 4| expands, causingexpansion of a bellows 42 which is connected to the bulb 4| by a conduit43. As the bellows 42 expands, it moves a lever 44 which engages amember 45 which carries the movable portion of the contact 38. Lever 44also engages one end of the snap-acting device 31, causing it to snapinto the position shown in Fig. 2 and close the contacts 38. It-isapparent that the defrosting period is terminated in response toevaporator temperature and the refrigerating mechanism again cycles tomaintain an average evaporator temperature below freezing, as determinedby the setting of the temperature control 25.

The ratchet wheel 33 shown in Fig. 2 by way on refrigerators shipped tosuch a locality.

From the foregoing it will be apparent that I have provided a newdefrosting device which in-.

. termittently automatically effects defrosting of the cooling elementof a refrigerator in response to the number of times the access door isopened.

While I have shown my invention in but one form, it will be obvious tothose skilled in the art that it is not so limited, but is susceptibleof various changes andmodifications without departing from the spiritthereof, and I desire, therefore, that only such limitations shall beplaced thereupon as are specifically set forth in the appended claims.

What I claim is:

1. In refrigeration apparatus, the combination of a refrigerator cabinethaving a food-storage compartment provided with an access openingtherein, a door movable for opening and closing the access opening, acooling element for refrigerating the air in said food-storagecompartment, refrigerating apparatus for normally maintaining saidcooling element at an average temperature below the freezing point ofwater, at which temperature it collects frost from the moisture in saidair and means responsive to the opening and closing of said door apredetermined plurality of times to modify the operation of saidrefrigerating apparatus to permit the temperature of said coolingelement to rise above the freezing point of water.

2. In refrigeration apparatus, the combination of a refrigerator cabinethaving a food-storage compartment provided with an access openingtherein, a movable door for opening and closing the access opening, acooling element for refrigerating the air in said food-storagecompartment, refrigerating apparatus for normally maintaining saidcooling element at an average temperature below the freezing point ofwater, at which temperature it collects frost from the moisture in saidair and means for modifying the operation of said refrigeratingapparatus to permit the temperature of said cooling element to riseabove the freezing point of water, in response to the opening andclosing of said door a predetermined plurality of times, and forreestablishing normal operation of said refrigerating apparatus inresponse to an above freezing temperature of said cooling element.

3. In refrigeration apparatus, the combination of a refrigerator cabinethaving a food-storage compartment provided with an access openingtherein, a door movable for opening and closing the access opening, acooling element for refrigerating the air in said food-storagecompartment, refrigerating means for normally maintaining thetemperature of said cooling element below the freezing point of water,at which temperature it collects frost from the moisture in said air,and means operative by the opening and closing of said door apredetermined plurality of times to modify the operation of saidrefrigerating means and thus permit a rise in the temperature of saidelement above the freezing point of Water.

4. In refrigeration apparatus, the combination of a refrigerator cabinethaving a food-storage compartment provided. with an access openingtherein, a door movable for opening and closing the access opening, acooling element for refrigerating the air in the food-storagecompartment, means for circulating a refrigerant through said coolingelement; control means for normally operating said refrigerantcirculating means to maintain an average temperature of said coolingelement' below the freezing point of water, at which temperature thecooling element collects frost from the moisture in said air and meansfor intermittently modifying the operation of said refrigerantcirculating means when said door has been opened and closed apredetermined plurality of times to raise the temperature of saidcooling element and effect defrosting of said cooling element.

5. In refrigeration apparatus, the combination of a refrigerator cabinethaving a food-storage compartment provided with an access openingtherein, a door movable for opening and closing the access opening, acooling element for refrigerating the air in the food-storagecompartment, means for circulating a refrigerant through said coolingelement, control means for normally operating said refrigerantcirculating means to maintain an average temperature of said coolingelement below the freezing point of water, at which temperature thecooling element collects frost from the moisture in said air, means forintermittently superseding said control means and for modifying theoperation of said refrigerant circulating means when said door is openedand closed a predetermined plurality of times to raise the temperatureof said cooling element and permit defrosting of said cooling elementand means responsive to an above freezing temperature of said coolingelement for restoring control of said circulating means to said controlmeans.

GRAHAM S. McCLOY.

